On Jan 27, 3:16 pm, Reckoner <recko... at gmail.com> wrote:
> I'm not sure this is possible, but I would like to have
> a list of objects
>> A=[a,b,c,d,...,z]
>> where, in the midst of a lot of processing I might do something like,
>> A[0].do_something_which_changes_the_properties()
>> which alter the properties of the object 'a'.
>> The trick is that I would like A to be mysteriously aware that
> something about the object 'a' has changed so that when I revisit A,
> I will know that the other items in the list need to be refreshed to
> reflect the changes in A as a result of changing 'a'.
>> Even better would be to automatically percolate the subsequent changes
> that resulted from altering 'a' for the rest of the items in the list.
> Naturally, all of these items are related in some parent-child
> fashion.
>> that might be a lot to ask, however.
>> Any advice appreciated.
You should really look at Enthought's Traits package. It does exactly
what you are asking for, and much, much more. See:
http://code.enthought.com/projects/traits/documentation.phphttp://code.enthought.com/projects/traits/examples.php
Using Traits, you could do the following:
from enthought.traits.api import *
class Child(HasTraits):
state = Enum("happy", "sad", "bawling")
class Parent(HasTraits):
child = Instance(Child)
@on_trait_change('child.state')
def handler(self):
print "new child state:", self.child.state
bob_jr = Child()
bob = Parent(child = bob_jr)
bob_jr.state = "sad"
# This would result in bob.handler() being called
(Disclosure: I work at Enthought and have been using Traits heavily
for the last 4+ years.)
-Peter